Add managing the temporary ignore list, so it's actually temporary

Author: LikeLakers2

monkestation/code/modules/slimecore/mobs/_base_slime.dm

@@ -232,6 +232,7 @@
 
 	if(slime_flags & CLEANER_SLIME)
 		ai_controller.clear_blackboard_key(BB_CLEAN_TARGET)
+		new_planning_subtree |= add_or_replace_tree(/datum/ai_planning_subtree/manage_unreachable_list)
 		new_planning_subtree |= add_or_replace_tree(/datum/ai_planning_subtree/cleaning_subtree_slime)
 
 	if(!(slime_flags & PASSIVE_SLIME))

monkestation/code/modules/slimecore/mobs/ai_controller/behaviours/clean_target.dm

@@ -23,9 +23,14 @@
 	qdel(target) // Sent to the shadow realm to never be seen again
 	finish_action(controller, TRUE, target_key)
 
+// Copied from `/datum/ai_behavior/execute_clean/finish_action`, but only the parts wanted for
+// supporting cleaner slimes.
 /datum/ai_behavior/execute_clean_slime/finish_action(datum/ai_controller/controller, succeeded, target_key, targeting_strategy_key, hiding_location_key)
 	. = ..()
 	var/atom/target = controller.blackboard[target_key]
+	if(!succeeded && !isnull(target))
+		controller.clear_blackboard_key(target_key)
+		controller.set_blackboard_key_assoc_lazylist(BB_TEMPORARY_IGNORE_LIST, REF(target), TRUE)
 	if(QDELETED(target) || is_type_in_typecache(target, controller.blackboard[BB_HUNTABLE_TRASH]))
 		return
 	if(!iscarbon(target))

monkestation/code/modules/slimecore/mobs/ai_controller/controller.dm

@@ -6,6 +6,7 @@
 		BB_BASIC_MOB_SCARED_ITEM = /obj/item/extinguisher,
 		BB_BASIC_MOB_STOP_FLEEING = TRUE,
 		BB_WONT_TARGET_CLIENTS = FALSE, //specifically to stop targetting clients
+		BB_UNREACHABLE_LIST_COOLDOWN = 45 SECONDS, // how often we want to clear our unreachable list
 	)
 
 	ai_movement = /datum/ai_movement/basic_avoidance